1. FIELD OF THE INVENTION
The present invention relates to an oil filtration apparatus for filtering oils, especially edible oils and fats, including cooking oil, as are prevalent in deep fat frying operations commonly employed wherever food is prepared for relatively large numbers of persons, such as restaurants, hospitals, and other similar institutions, of undesirable and sometimes rancid impurities, including very small micron-sized particles, thereby enabling said oil to be re-used two or three times with no sacrifice in its quality.
2. BACKGROUND AND SUMMARY OF THE INVENTION
There presently exists several devices for continuously filtering or purifying cooking oil and other edible oils and fats employed in deep fat frying operations, wherein the oil is generally pumped through a filtering system which filters out much of the crumbs or the like which frequently drop off of the food being cooked during the cooking operation and accumulate on the bottom of the deep fat fryer, which presents sanitary and aesthetic problems and which adversely affects the cooking operation by means of causing a degradation or decomposition of the cooking oil into its fatty acid components, which darkens the cooking oil and the food being cooked therein, resulting in undesirable taste and odors being transferred to said food. The fatty acids in the residues in the oil or shortening, in addition to scorching and the adverse effects thereof, react in the shortening or oil to cause and greatly accelerate oxidation and/or general breaking down and degradation thereof, thereby greatly reducing the useful life thereof for cooking purposes (i.e. as a viable medium of heat transfer). Representative of the prior art within this field of invention are U.S. Pat. Nos. 3,477,361; 3,483,982; 3,759,388; and 3,880,757. These filtering systems of the prior art basically work in the following simple manner:
First, all of the oils and/or fats, particle of food, flour and seasoning, which accumulated in the deep frying vat during the cooking process, are drained into a filter tub, which has a single ply of filter paper in the bottom. The oil or fat is then vacuumed out of the tub and back into the cooking vat through this single ply of filter paper, thereby removing only larger particles twenty micron and above in size. That is why, after three or four days of cooking in the oil or fat, these particles of micron size accumulate in the oil and burn from high temperature, gradually turning the oil and food dark in color and causing it to look and taste bad. However, none of these references suggest the specific combination taught by the present invention, which combination features several major advantages/improvements thereover. The results produced by the present invention have been long sought after by those skilled in the art, but until the advent of this invention, these results have been unobtainable. The present invention features a dual-filtering system which works in a similar manner, but after the oil leaves the filter tub, it is pressure-pumped upwardly into the bottom part of a second filter cannister (called the void). This action causes more particles to separate and settle, thus leaving only the very small micron-sized particles which are suspended in the oil to enter a filter element mounted within said cannister. This novel filter element is made of highly refined, uniform, very dense and absorbent paper approved by USDA and FDA for use in filtering edible oils and fats. When the cooking oil reaches the bottom of the filter element and is forced upwardly through several inches of this tightly-wound paper, which strips the oil of all contaminants down to 1/10 of a micron in size or as small as tobacco smoke, which renders the oil or fat free of all harmful contaminants. However, the apparatus of the present invention further comprises quick connect/disconnect hoses to facilitate bypassing of the upflow second filter element just described, thereby effecting easy conversion to the single filter element system common to the prior art, when such is desirable.
The present invention basically comprises:
1. A filter tub or enclosure of conventional construction (i.e. a bottom wall with upwardly extending, enclosing side walls), preferably made of stainless steel or any other suitable, easy-to-clean metal;
2. A screen filter element having a plurality of blisters or bubbles, placed on the bottom of said enclosure, thereby providing an increased surface area for filtering the cooking oils or fats contained by said enclosure, thereby enhancing the filtering and purification thereof;
3. A paper filter element placed on top of said screen element, for facilitating removal of micron-sized particles from said cooking oils and/or fats;
4. A retainer ring securably mounted in fluidly sealing relationship to the bottom of said enclosure, which it is made to conform with, over said screen filter element and said paper filter element, thereby securing said filter elements to the bottom surface of said enclosure;
5. A combination vacuum/pressure pump disposed adjacent to said enclosure;
6. A fine filtering assembly mounted, by means of a bracket attached to a side wall of said enclosure, upstream of said enclosure, wherein said fine filtering assembly comprises a generally cylindrical cannister having a lower void area and an upper void area, and a tightly-wound paper filter element mounted therein between said upper and lower void areas in fluidly sealing engagement thereto, wherein said paper filter element is composed of highly refined, uniform, very dense, and absorbent paper approved by USDA and FDA for use in filtering edible oils and fats;
7. A cap mated in pressure-sealing relationship to the top of said cannister, wherein said cap comprises a downwardly extending member having outwardly directed bevels wedged into the top portion of said tightly-wound paper filter element;
8. Inlet and outlet means integral to said cannister for facilitating the intake and exhaust of said cooking oils and fats therewithin and therewithout, respectively;
9. A drain or sump provided on the bottom surface of said filter tub;
10. First conduit means connecting said drain to said combination vacuum/pressure pump for conveying said oils or fats from said filter tub to said pump;
11. Second conduit means connecting said pump to said inlet means of said cannister;
12. Third conduit means connected on one end to said outlet means of said cannister and preferably having nozzle means at its other (i.e. opposite) end for directing said oils or fats into any suitable destination, which is generally cooking vats disposed in the immediate vicinity of said filter tub;
13. Roller means fixedly attached to said filter tub, thereby making said filter tub mobile, thereby facilitating the easy movement thereof to any desired location;
14. Energization means for energizing said pump, for activating said dual-filtering apparatus of the present invention, which operates in the following manner:
a. used, at least partially decomposed, dirtied, hot cooking oils and/or fats, are emptied or poured from said deep frying vats into said filter tub;
b. energizing said pump with said energization means, thereby causing said pump to first vacuum said oils and/or fats through said paper filter element and said screen filter element which are secured to the bottom of said filter tub, and thence through said drain and said first conduit means into said pump--this filtering process effects the removal from said oils and/or fats of all solid particles (e.g. flour, cornmeal, fat from the food being deep fried in the vats) down to about twenty-thirty microns in size;
c. the pressure side of said pump then forces or conveys said oils and/or fats, which are now partially filtered, upwardly through said second conduit means and said inlet means of said cannister, and through said lower void area of said cannister, wherein by the natural action of downward gravitational force, much of the contaminates suspended in the oils and/or fats settle out of the flowing stream thereof; the pressure supplied by said pump is sufficiently strong to drive said oils and/or fats upwardly through said novel tightly-wound paper filter element mounted within said cannister, which is a specially formulated blend of different types of paper, rolled with just enough pressure to achieve a certain tightness between plies to effect removal of all solid particles from said oils and/or fats down to 1/10 of a micron in size, thereby substantially purifying said oils and/or fats for re-use;
d. the now purified or filtered oils and/or fats (which are now suitable for cooking purposes--i.e. are now a viable heat transfer medium) are thence delivered or conveyed through said outlet means of said cannister and through said third conduit means fluidly connected thereto, and through said nozzle means thereof, to any suitable destination, which is generally the deep frying vats for re-use in deep frying operations--it should be noted that this filtering apparatus of the present invention increases the useful life of said cooking oils and/or fats by two to three times, thereby ultimately resulting in increased efficiency of operation and reduction in the cost of operation commensurate with the cost of the cooking oil saved;
e. said filter tub is preferably constructed of stainless steel, thereby facilitating the easy and effective cleaning thereof, by means of, for example, hot water and a clean hand towel (no soap as this can contaminate and degrade the cooking oil), thereby rendering said filter tub fit for subsequent re-use. Further, said filter elements therein and said filter element mounted within said cannister are preferably disposable and are easily replacable. Disposable filters are favorable over washable filters, because if washable filters are not properly cleaned, the oil may be damaged rather than helped by filtration. Additionally, the dual-filtering apparatus of the present invention possesses the capability of being readily convertible into a single-filtering apparatus, similar to (but improved over) the devices commonly found in the prior art. However, the dual-filtering, upflow system of the present invention provides many inherent advantages or benefits over any of the devices of the prior art, particularly:
i. the upflow, fine filtering assembly, hereinabove described, facilitates the removal of fine, contaminate particulates down to 1/10 of a micron in size, vis-a-vis twenty to thirty microns as is possible with the devices of the prior art, thereby resulting in a cooking oil which is much more purified and fit to cook with, thereby ultimately resulting in better-tasting and much more sanitary, nutritious food;
ii. the screen filter element mounted below the paper element within the bottom of the filter tub, is novel, in that it comprises bubbles which hold it off of the bottom of the filter tub, thereby providing an increased surface area for filtering said cooking oils and/or fats;
iii. said quick connect/disconnect hoses which facilitate easy conversion to the single-filtering system prevalent in the prior art;
iv. the apparatus of the present invention is cost-effective, simple to operate, and is much more efficient than the devices provided in the prior art.